Mu Ko Surin National Park is situated in the Andaman sea approximately 60 km from the coast of Phang Nga Province in the southern peninsula region. The park covers an area of approximately 135 km. Of the protected area, 102 sq km or 76% is sea. The park comprises 5 main islands; Ko Surin Nua, Ko Surin Tai, Ko Ree (Ko Stok), Ko Pachumba, and Ko Kai (Ko Torinla). A few kilometers to the north of the park is the Myanmar border and about 100 km to the south are the Similan Islands.

Richelieu Rock (called Hin Plo Naam in Thai) is part of the Mu Koh Surin marine park although being about 18 km east of Surin island. The rock surfaces only a few meters with low tide and is practically invisible from the surface during high tide. The maximum depth of this dive site is about 33 m with water temperatures varying from 26 C to about 30 C.

These stunningly beautiful islands are open to visitors from 16 November to 15 May. The picture postcard beaches and excellent snorkelling are a big draw. The main activity enjoyed by visitors is snorkelling, closely followed by scuba diving. Accommodation takes the form of bungalows and tents. There are two campsites on Ko Surin Nua.

The islands were declared a national park on 9 July 1981 in recognition of the islands unique beauty and to protect the fragile marine habitat. Green and hawksbill turtles are frequent visitors to the islands. They come to nest on the island beaches. In the 1990s some rare Olive Ridley turtles were also laying their eggs here. Diving is not allowed in certain areas of the park where conservation initiatives are taking place.

Richelieu Rock is a huge seamount and is covered with a lot of purple soft corals. Between the corals live a lot of smaller animals like porcelain crabs, ghost pipe fish, sea horses, muray eels, shrimps, and nudibranches. There are also common sightings of whale sharks and manta rays during the dive season. Sometimes guitar rays can be seen here.

You can only dive in the national marine park with an accredited dive company from Khao Lak, Phuket, or Ranong during the dive season which runs from November to May. To dive the Surin Islands and/or Richelieu Rock you will have to pay a National Marine Park fee, normally included in the price of the diving expedition.

Although the dive site is huge, you will be able to see most of the landscape of the whole site on one dive. But because there is so much too see here. you can easily make hundreds of dives here and still have the feeling that you want to return.